Among the several drugs used to effect blood clot lysis, urokinase is one of the best because it generally does not produce antibodies. It is currently used clinically to remove blood clots in pulmonary arteries, but is not used extensively because of the limited supply, high cost, and difficulty of isolating it from human urine. Research at Hope College during the last year has shown that urokinase is present in the cortex of bovine kidneys. The goal of this research will be to isolate urokinase from bovine kidneys and compare its properties to human urokinase isolated from urine. Hoefully, a product will be obtained that can eventually be tested clinically. The results of the project should provide the expertise necessary to supply the medical profession with an inexpensive source of urokinase, analogous to the animal source used for the medical supply of insulin. Classical techniques such as ammonium sulfate precipitation, gel filtration chromatography, ion exchange chromatography, and preparative electrophoresis will be employed in the isolation procedure. Once the urokinase has been purified, its molecular weight, amino acid composition, and immunological properties will be compared to the commercial human urokinase.